This invention relates to a means for mounting and accurately seating a rotary cutting or perforating knife such as might be used to sever, completely or partially, a web at a plurality of locations along its length. One of the requirements for such knife mounting arrangements is that the cutting edge of the knife be capable of accurate seating against an anvil surface. For example, a back-up or anvil cylinder may be provided with a hardened surface, or insert, or in some cases a die, to cooperate with the sharpened edge of the knife in severing the passing web as the web moves between the rotating knife cylinder and anvil or back-up cylinder.
It has been known for many years that the knife can be accurately clamped in a slot in a rotary cutter cylinder by using various forms of wedging devices. For example, one side of the slot will be machined non-parallel to the opposite side of the slot, and one or more wedging bars are fitted into such slot, and drawn inward, as by a plurality of clamp screws or bolts, thereby exerting a sidewise clamping or wedging action against the knife blade. The blade may be clamped against one of the side faces of the slot, or against an intermediate supporting bar, in accordance with various prior art practices.
In some instances the knife blade itself has been slotted, or drilled, in order to provide passage for clamping screws which act through an intermediary clamping bar to clamp the blade against a seating or supporting side surface within the mounting slot. The slot for receiving the knife blade may be machined within a surface of a rotary cutter cylinder, or may be incorporated as part of a built up mounting structure, mounted on a smaller diameter cylinder or a skeleton cylinder arrangement. In any event, the procedure for mounting and "seating in" the knife blade requires that the blade be fitted into the slot or other supporting structure, and clamped somewhat loosely throughout its length, such that the knife can move into the slot in any or all of the locations along the slot as the knife is seated against the anvil surface (or against the die). Once the knife blade is seated in, it is then necessary to tighten all of the clamping structure to be sure that the blade is securely clamped throughout its length for the ensuing run of the apparatus. p Prior art patents which show these arrangements in various combinations and modifications are U.S. Pat. Nos. 2,660,242; 2,751,006, 3,073,196; 3,084,582; 3,086,416; 3,166,965; 3,264,921; 3,555,948; 3,709,077; 3,733,949; 3,771,399; and 3,793,918.